KORE milestone 1

**please review**

 - unit-tested convertors from KORE to KIL and back
 - significant changes and simplifications to KORE data structures. They are smaller and more powerful now

We're not covering comments yet because it's not obvious how they should be approached. Basically, we cannot just throw the comments in the same bucket with everything else because order matters. Each comment refers to the sentence just below it but that order is not preserved in KORE. We'll have to figure out a smarter way of attaching comments to ASTs but we haven't yet.